Stanford University’s solar power PPA with developer Recurrent Energy based on construction and operation of the Stanford Solar Generating Station #2 is expected to meet 53 percent of the university’s electricity demand when it comes online in 2021. Recurrent is building the 63-megawatt-AC (MWac)/88 MW-peak (MWp) solar photovoltaic (PV) power plant at a greenfield site spanning over 400 acres (161.87 hectares) near Lemoore, Kings County in Central California.

This project, together with Stanford University’s existing 67-MWp solar PPA and its 5-MWp rooftop installation, will produce enough clean renewable electricity each year to equal the university’s annual electricity consumption…[T]he project will power the equivalent of 15,750 homes with clean electricity.

– a spokesperson for Recurrent Energy told Solar Magazine.

Stanford’s clean energy-sustainability team was surprised by just how cheap solar power has become in California, Stanford University’s Executive Director of Sustainability and Energy Management Joe Stagner told Solar Magazine. Stanford Energy Systems Innovations (SESI) thought it got a great deal when it contracted directly with an independent solar power producer and its first utility-scale solar power project came online in December 2016 at a cost of just over USD0.05 per kilowatt-hour (kWh). Solar power prices in California have dropped even further since.

Solar electricity at below USD0.025 per kilowatt-hour

In its latest open solicitation, the SESI project team received a few offers for geothermal power above USD0.06 per kWh and wind power offers below USD0.04 per kWh. The project team also received “quite a few solar offers, all at or below USD0.025 per kWh,” Stagner recounted. He wouldn’t say by how much, but Recurrent Energy’s offer came in below that.

We were very surprised we could get solar power at 2.5 cents per kWh…With prices coming down so far, so fast, it feels like the days when [natural or shale gas] fracking arrived on the scene and grid operators out west were migrating to natural gas, [which seemingly all of a sudden was] a cheap, plentiful resource.

Stanford’s announcement came just as representatives from the 195-plus nations party to the UN Framework Convention on Climate Change (UNFCCC) and Paris Climate Agreement were meeting in Katowice, Poland in an attempt to identify and agree on ways to spur governments, commerce, industry, other types of organizations and individuals worldwide to take actions to stem the rising tide of anthropogenic carbon dioxide (CO2), methane and other greenhouse gas emissions as quickly as possible. The signing of the utility-scale solar PPA with Recurrent Energy that will enable the university to go completely carbon-free in terms of electricity was pure coincidence, Stagner said in an interview.

The university has already reduced its energy-related greenhouse gas emissions 65 percent below peak levels thanks to the entire university community’s commitment and ability to follow through and realize the goals of an ambitious, long-term and system-wide clean energy and emissions reduction planning process. The Stanford Solar Generating Station #2 may be likened to the long-term planning process’s capstone – the solar power plant is expected to bring the university’s greenhouse gas emissions down 80 percent below peak levels, four years ahead of the goal set out in the current version of the university’s long-range clean energy and sustainability plan.

Stanford University can be likened to a town or small city that’s running 24x7x365. More than 30,000 students attend the university, which spans more than 1,000 buildings and 8,080 acres (3,271 hectares). The university’s clean energy, emissions reduction and environmental sustainability efforts go back a long way.

Stanford deployed an initial district energy heating system based on steam heat over half a century ago, Stagner told Solar Magazine. That expanded to include chilled water and has evolved from there. A natural gas-fueled co-generation, or combined heat and power (CHP) system replaced the previous generation steam-heat and chilled-water system just over 30 years ago as university students, faculty and the community committed to enhancing the environmental, and economic, sustainability of university energy use and production.

That’s really when we [SESI] started our efforts, in 2008. Stanford’s energy and sustainability team completed an analysis of university-wide energy use, distribution and production in 2009-2010. The university’s board agreed to move forward with a comprehensive, long-range planning process to electrify the entire university campus in 2011.

While carrying out its university-wide energy assessment, the Stanford program team “got this whole picture of energy use, and when we compared our annual heating and cooling hour by hour, we found an incredible 75 percent overlap. We found that with 75 of the air we were producing as much heat and sending out it to the buildings for their use as we were receiving heat back from the buildings and discharging to the atmosphere as waste, via evaporative cooling, my jaw really hit the desk. I knew right then we had this great opportunity looking at us to recover this waste heat and use it for the university,” Stagner explains in a university video.

Instead of exhausting heat into the atmosphere when cooling and then using natural gas to heat water and air for space heating, Stanford’s energy and sustainability team decided to make use of it, as well as ambient heat in the atmosphere and in-ground, store it and make use of that thermal energy at night to heat buildings and water.

One of the program team’s first major challenges was how to replace the natural gas-fired co-generation system. “It was obvious that we were never going to eliminate our [greenhouse gas] emissions if we continued to rely on natural gas, so we had to find alternatives. Clean electrification emerged as a clear, better choice,” Stagner recounted.

Heat (thermal energy) recovery and use was the first key and still core element of SESI and Stanford’s success in realizing its own, as well as California’s, clean energy and sustainability goals. Heating, cooling and powering Stanford’s 200 largest buildings probably accounts for over 90 percent of the university’s energy use, Stagner pointed out. Discharged waste heat and lake source geothermal energy exchange feed three very large heat pumps that heat and cool buildings simultaneously, Stagner continued.

“An interesting way to think about this is the collection of heat and moving it away from a building, like refrigeration or air-conditioning,” Stagner continued in our interview. “You’re sucking heat out of the building using electric motors and compressors and exhausting it outside.” In Stanford’s case, that thermal energy is then used to heat spaces and water, however.

“There’s a lot of cooling and heating going on simultaneously, or within a short time of each other on a daily basis. We store and use heat in a very efficient, electrification process and in that way get the fossil fuels out. It’s not only very efficient, but saving and using all that waste heat is also a lot more economic.”

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On-site solar power generation: Incredibly cheap and efficient

These and other, more recent green campus innovations and advances by SESI, university and project partners serve as technological keystones paving the way to the success Stanford has had, and expects to continue having, with regard to realizing its clean energy and climate change action goals. The recent focus has shifted from energy efficiency towards finding clean, renewable energy sources of on-site power generation. Solar energy plays the feature role.

Stanford contracted with SunPower for its first utility-scale solar power plant back in 2014 after California began conducting clean energy lotteries that opened the door for large energy consumers to bypass distribution utilities and purchase electricity services directly from independent power producers. Part and parcel of this initial deal, SunPower installed 5 MW of rooftop solar PV systems on the Stanford campus.

Photo: Stanford University

Coming online in Dec. 2016, the Stanford Solar Generating Station #1 meets about 50 percent of the university’s electricity demand at present. The rooftop solar PV system adds another 3 percent, Stagner noted. Stanford has been purchasing electricity from California’s electricity grid market to meet the remaining 47 percent of its electricity load.

On average, emissions-free, renewable energy has accounted for about 27 percent of grid power in the Golden State, or one-fourth of the university’s remaining power needs, however. Stagner pointed out. That brings Stanford to around 65 percent of the way towards realizing its 100 percent carbon-free electricity goal – until Recurrent completes construction of the Stanford Solar Generation Station #2 in 2021, if not sooner.

A growing university, with growing energy demand

Stanford University continues to grow, however. According to SESI’s current calculations, the new solar power facility in Kings County will serve about 55 percent of the university’s projected, annual electricity load of some 330 million kWh when it comes online in 2021.

Recurrent Energy came out on top upon SESI completing its review of all the offers it received for its latest utility-scale solar power solicitation. “We issued an open solicitation to all the major suppliers. Their [Recurrent’s] proposal turned out to be the most economic, they came in with the lowest cost PPA and the proposed site was in the best location,” Stagner explained. “Rather than Southern California [where a lot of California’s solar power generation takes place], Recurrent is building the plant in Central California, which is closer to Stanford.”

Furthermore, “Recurrent’s track record made it an easy choice for us. They’re a large corporation with demonstrated success [designing, engineering, building and operating utility-scale solar power plants]. We’re confident in their ability to build and operate the solar power facility over the PPA’s entire, 25-year term,” Stagner said.

Given present day costs and other conditions, Stanford estimates that SESI powered with off-site and on-site PV generation will save the university more than USD420 million over a 30-year life cycle. On-site PV generation also conserves freshwater – reducing consumption 18 percent – which also results in cost savings. Then there are the emissions reductions, which SESI and the university expect will amount to an 80 percent reduction from peak levels as a result of the Kings County solar power plant coming online and reaching full production capacity.

Reproducible results?

Does Stagner believe other universities and campuses can reproduce Stanford’s results? “Sure…More and more people are discovering that moving to electric heat generation and cheap solar power works everywhere, even in cold climates,” Stagner said.

The first step towards complete electrification is heating and cooling, he continued. “Ways of generating emissions-free electricity and cooling are now cost-effective and obvious. Hot water is the key challenge, but electric heat pumps are really unlocking that. Instead of throwing heat away, you can use it for space heating and to heat water. Then, you can use a heat pump to suck heat out of the ground, a lake, reservoir or the air to augment that and not only heat water and spaces but electrify the entire process. We call it combined heating and cooling, in contrast to using fossil fuels in a combined heat and power (CHP) system,” Stagner explained.

Timely as it is, the coincidence of Stanford signing of the solar power PPA that will bring it to 100 percent carbon-free electricity and the UN climate change conference taking place in Katowice was purely a chance occurrence. Back five years ago, SESI, university leaders and the community were having a lot of discussions revolving around the question of whether or not the university should go completely renewable in one leap or not.

“We decided to do half then and then wait and see how the technology evolves,” Stagner said. Five years later, with a new administration, Stanford is on the cusp of being completely carbon-free with regard to electricity.

Stagner and the SESI team believe the number of colleges and universities going down the same, or a similar, carbon-free electricity pathway will only increase. “We’re seeing it happen all over – UC Davis [the University of California, Davis], Ball State University in Indiana. And we’ve had inquiries and visits from universities around the world, as well as France’s ambassador to the U.S. and members of the White House National Science and Technology Advisory Council.” comment

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